// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_DISK_CACHE_BLOCKFILE_ENTRY_IMPL_H_
#define NET_DISK_CACHE_BLOCKFILE_ENTRY_IMPL_H_

#include <stdint.h>

#include <memory>

#include "base/macros.h"
#include "net/disk_cache/blockfile/disk_format.h"
#include "net/disk_cache/blockfile/storage_block-inl.h"
#include "net/disk_cache/blockfile/storage_block.h"
#include "net/disk_cache/disk_cache.h"
#include "net/log/net_log.h"

namespace disk_cache {

class BackendImpl;
class InFlightBackendIO;
class SparseControl;
typedef StorageBlock<EntryStore> CacheEntryBlock;
typedef StorageBlock<RankingsNode> CacheRankingsBlock;

// This class implements the Entry interface. An object of this
// class represents a single entry on the cache.
class NET_EXPORT_PRIVATE EntryImpl
    : public Entry,
      public base::RefCounted<EntryImpl> {
    friend class base::RefCounted<EntryImpl>;
    friend class SparseControl;

public:
    enum Operation {
        kRead,
        kWrite,
        kSparseRead,
        kSparseWrite,
        kAsyncIO,
        kReadAsync1,
        kWriteAsync1
    };

    EntryImpl(BackendImpl* backend, Addr address, bool read_only);

    // Background implementation of the Entry interface.
    void DoomImpl();
    int ReadDataImpl(int index, int offset, IOBuffer* buf, int buf_len,
        const CompletionCallback& callback);
    int WriteDataImpl(int index, int offset, IOBuffer* buf, int buf_len,
        const CompletionCallback& callback, bool truncate);
    int ReadSparseDataImpl(int64_t offset,
        IOBuffer* buf,
        int buf_len,
        const CompletionCallback& callback);
    int WriteSparseDataImpl(int64_t offset,
        IOBuffer* buf,
        int buf_len,
        const CompletionCallback& callback);
    int GetAvailableRangeImpl(int64_t offset, int len, int64_t* start);
    void CancelSparseIOImpl();
    int ReadyForSparseIOImpl(const CompletionCallback& callback);

    inline CacheEntryBlock* entry()
    {
        return &entry_;
    }

    inline CacheRankingsBlock* rankings()
    {
        return &node_;
    }

    uint32_t GetHash();

    // Performs the initialization of a EntryImpl that will be added to the
    // cache.
    bool CreateEntry(Addr node_address, const std::string& key, uint32_t hash);

    // Returns true if this entry matches the lookup arguments.
    bool IsSameEntry(const std::string& key, uint32_t hash);

    // Permamently destroys this entry.
    void InternalDoom();

    // Deletes this entry from disk. If |everything| is false, only the user data
    // will be removed, leaving the key and control data intact.
    void DeleteEntryData(bool everything);

    // Returns the address of the next entry on the list of entries with the same
    // hash.
    CacheAddr GetNextAddress();

    // Sets the address of the next entry on the list of entries with the same
    // hash.
    void SetNextAddress(Addr address);

    // Reloads the rankings node information.
    bool LoadNodeAddress();

    // Updates the stored data to reflect the run-time information for this entry.
    // Returns false if the data could not be updated. The purpose of this method
    // is to be able to detect entries that are currently in use.
    bool Update();

    bool dirty()
    {
        return dirty_;
    }

    bool doomed()
    {
        return doomed_;
    }

    // Marks this entry as dirty (in memory) if needed. This is intended only for
    // entries that are being read from disk, to be called during loading.
    void SetDirtyFlag(int32_t current_id);

    // Fixes this entry so it can be treated as valid (to delete it).
    void SetPointerForInvalidEntry(int32_t new_id);

    // Returns true if this entry is so meesed up that not everything is going to
    // be removed.
    bool LeaveRankingsBehind();

    // Returns false if the entry is clearly invalid.
    bool SanityCheck();
    bool DataSanityCheck();

    // Attempts to make this entry reachable though the key.
    void FixForDelete();

    // Handle the pending asynchronous IO count.
    void IncrementIoCount();
    void DecrementIoCount();

    // This entry is being returned to the user. It is always called from the
    // primary thread (not the dedicated cache thread).
    void OnEntryCreated(BackendImpl* backend);

    // Set the access times for this entry. This method provides support for
    // the upgrade tool.
    void SetTimes(base::Time last_used, base::Time last_modified);

    // Generates a histogram for the time spent working on this operation.
    void ReportIOTime(Operation op, const base::TimeTicks& start);

    // Logs a begin event and enables logging for the EntryImpl.  Will also cause
    // an end event to be logged on destruction.  The EntryImpl must have its key
    // initialized before this is called.  |created| is true if the Entry was
    // created rather than opened.
    void BeginLogging(net::NetLog* net_log, bool created);

    const net::BoundNetLog& net_log() const;

    // Returns the number of blocks needed to store an EntryStore.
    static int NumBlocksForEntry(int key_size);

    // Entry interface.
    void Doom() override;
    void Close() override;
    std::string GetKey() const override;
    base::Time GetLastUsed() const override;
    base::Time GetLastModified() const override;
    int32_t GetDataSize(int index) const override;
    int ReadData(int index,
        int offset,
        IOBuffer* buf,
        int buf_len,
        const CompletionCallback& callback) override;
    int WriteData(int index,
        int offset,
        IOBuffer* buf,
        int buf_len,
        const CompletionCallback& callback,
        bool truncate) override;
    int ReadSparseData(int64_t offset,
        IOBuffer* buf,
        int buf_len,
        const CompletionCallback& callback) override;
    int WriteSparseData(int64_t offset,
        IOBuffer* buf,
        int buf_len,
        const CompletionCallback& callback) override;
    int GetAvailableRange(int64_t offset,
        int len,
        int64_t* start,
        const CompletionCallback& callback) override;
    bool CouldBeSparse() const override;
    void CancelSparseIO() override;
    int ReadyForSparseIO(const CompletionCallback& callback) override;

private:
    enum {
        kNumStreams = 3
    };
    class UserBuffer;

    ~EntryImpl() override;

    // Do all the work for ReadDataImpl and WriteDataImpl.  Implemented as
    // separate functions to make logging of results simpler.
    int InternalReadData(int index, int offset, IOBuffer* buf,
        int buf_len, const CompletionCallback& callback);
    int InternalWriteData(int index, int offset, IOBuffer* buf, int buf_len,
        const CompletionCallback& callback, bool truncate);

    // Initializes the storage for an internal or external data block.
    bool CreateDataBlock(int index, int size);

    // Initializes the storage for an internal or external generic block.
    bool CreateBlock(int size, Addr* address);

    // Deletes the data pointed by address, maybe backed by files_[index].
    // Note that most likely the caller should delete (and store) the reference to
    // |address| *before* calling this method because we don't want to have an
    // entry using an address that is already free.
    void DeleteData(Addr address, int index);

    // Updates ranking information.
    void UpdateRank(bool modified);

    // Returns a pointer to the file that stores the given address.
    File* GetBackingFile(Addr address, int index);

    // Returns a pointer to the file that stores external data.
    File* GetExternalFile(Addr address, int index);

    // Prepares the target file or buffer for a write of buf_len bytes at the
    // given offset.
    bool PrepareTarget(int index, int offset, int buf_len, bool truncate);

    // Adjusts the internal buffer and file handle for a write that truncates this
    // stream.
    bool HandleTruncation(int index, int offset, int buf_len);

    // Copies data from disk to the internal buffer.
    bool CopyToLocalBuffer(int index);

    // Reads from a block data file to this object's memory buffer.
    bool MoveToLocalBuffer(int index);

    // Loads the external file to this object's memory buffer.
    bool ImportSeparateFile(int index, int new_size);

    // Makes sure that the internal buffer can handle the a write of |buf_len|
    // bytes to |offset|.
    bool PrepareBuffer(int index, int offset, int buf_len);

    // Flushes the in-memory data to the backing storage. The data destination
    // is determined based on the current data length and |min_len|.
    bool Flush(int index, int min_len);

    // Updates the size of a given data stream.
    void UpdateSize(int index, int old_size, int new_size);

    // Initializes the sparse control object. Returns a net error code.
    int InitSparseData();

    // Adds the provided |flags| to the current EntryFlags for this entry.
    void SetEntryFlags(uint32_t flags);

    // Returns the current EntryFlags for this entry.
    uint32_t GetEntryFlags();

    // Gets the data stored at the given index. If the information is in memory,
    // a buffer will be allocated and the data will be copied to it (the caller
    // can find out the size of the buffer before making this call). Otherwise,
    // the cache address of the data will be returned, and that address will be
    // removed from the regular book keeping of this entry so the caller is
    // responsible for deleting the block (or file) from the backing store at some
    // point; there is no need to report any storage-size change, only to do the
    // actual cleanup.
    void GetData(int index, char** buffer, Addr* address);

    // Logs this entry to the internal trace buffer.
    void Log(const char* msg);

    CacheEntryBlock entry_; // Key related information for this entry.
    CacheRankingsBlock node_; // Rankings related information for this entry.
    base::WeakPtr<BackendImpl> backend_; // Back pointer to the cache.
    base::WeakPtr<InFlightBackendIO> background_queue_; // In-progress queue.
    std::unique_ptr<UserBuffer> user_buffers_[kNumStreams]; // Stores user data.
    // Files to store external user data and key.
    scoped_refptr<File> files_[kNumStreams + 1];
    mutable std::string key_; // Copy of the key.
    int unreported_size_[kNumStreams]; // Bytes not reported yet to the backend.
    bool doomed_; // True if this entry was removed from the cache.
    bool read_only_; // True if not yet writing.
    bool dirty_; // True if we detected that this is a dirty entry.
    std::unique_ptr<SparseControl> sparse_; // Support for sparse entries.

    net::BoundNetLog net_log_;

    DISALLOW_COPY_AND_ASSIGN(EntryImpl);
};

} // namespace disk_cache

#endif // NET_DISK_CACHE_BLOCKFILE_ENTRY_IMPL_H_
